Assumption Tha Research Articles

Climate nonlinearities: selection, uncertainty, projections, and damages

Climate projections are uncertain; this uncertainty is costly and impedes progress on climate policy. This uncertainty is primarily parametric (what numbers do we plug into our equations?), structural (what equations do we use in the first place?), and due to internal variability (natural variability intrinsic to the climate system). The former and latter are straightforward to characterise in principle, though may be computationally intensive for complex climate models. The second is more challenging to characterise and is therefore often ignored. We developed a Bayesian approach to quantify structural uncertainty in climate projections, using the idealised energy-balance model representations of climate physics that underpin many economists’ integrated assessment models (IAMs) (and therefore their policy recommendations). We define a model selection parameter, which switches on one of a suite of proposed climate nonlinearities and multidecadal climate feedbacks. We find that a model with a temperature-dependent climate feedback is most consistent with global mean surface temperature observations, but that the sign of the temperature-dependence is opposite of what Earth system models suggest. This difference of sign is likely due to the assumption tha the recent pattern effect can be represented as a temperature dependence. Moreover, models other than the most likely one contain a majority of the posterior probability, indicating that structural uncertainty is important for climate projections. Indeed, in projections using shared socioeconomic pathways similar to current emissions reductions targets, structural uncertainty dwarfs parametric uncertainty in temperature. Consequently, structural uncertainty dominates overall non-socioeconomic uncertainty in economic projections of climate change damages, as estimated from a simple temperature-to-damages calculation. These results indicate that considering structural uncertainty is crucial for IAMs in particular, and for climate projections in general.

The communication between a doctor and his patients’ parents as a factor in the availability of medical care for disabled children

The purpose of this s tudy is the identi fi cation of types of communica tion among physi cians and parents of disabled children, who have congenital or acqui red pa thologies and who need treatment and rehabilita tion. The focal point of the s tudy is the assumption tha t the communi cation between the doctor and the child’s parents should be based on trust. It is one of the factors influencing the availability of medi cal care for children with disabilities. The study uses as tructured in-depth interview (19). There is much evi dence tha t doctors and parents prefer a paternalistic type of communication unlike partner, contractual or engineering. Our conclusion is that in a medical institution within the established bureaucratic type of organisational culture , recorded in our earlier study, the conditions for the professional activities of doctors and parents with disabled children receiving help are perceived by them as the most comfortable, since they correspond to their value orientations and expectations. Keywords: Disabled children, access to medi cal care, doctor, parents , communi ca tion.

Impact of prior cancer on eligibility for lung cancer clinical trials.

6566 Background: Fewer than 3% of adult oncology patients in the U.S. enroll onto clinical studies. Stringent eligibility criteria are a key factor limiting accrual. Among these, the assumption tha...

Standard Errors for Matrix Correlations

Matrix correlation is the index for the relationship between two sets of variables. Among the matrix correlations which have been proposed, the asymptotic standard errors of the following are derived: redundancy coefficient, Robert and Escoulfier's coefficient, Yanai's coefficient, Rozeboom's coefficient, and Coxhead's coefficient. With the assumption tha the variables are normall distributed, the standard errors of the coefficients are obtained using the δ-method. Further, the standard errors of the congruence coefficients for two factor-loading matrices are obtained. The accuracies of their results are confirmed by simulation.

Public Choice Theory for Political Sociology

Some sociologists and other social scientists argue that political andother sociology should be founded on a venerabl e or nascen t rationa l choicetheory seen as a unifying paradigm. Such a paradigm is predicated uponthe assumption tha t individual s are rational actor s seekin g predefined goals.The latter are subsumed under material interest, utility, profit, or wealth,with other ends being implicitly viewed as nonrational and thus inconse-quential. The paradigm of rational choice is expected to bring theoreticalunity in social science, by being the basis of economics as well as of publicchoice theory in political science and social exchange theory in sociologyor social psychology. On this account, some sociologists attribute to anddemand for rational choice theory a "paradigmatic privilege" (Abell, 1992;Goldthorpe, 1998; Hechter and Kanazawa, 1997 ) withi n sociology, includin gpolitical sociology. Rational choice theory is attributed such a status onthe grounds that explanation of social processes and structures, includingpolitical ones, is reached only when these are accounted for in terms ofthe rational economic actions of individuals. Although political processesare not admittedly merely extensions of economic ones, the conception ofeconomically rational action is treated as a fruitful basis for social theory(Coleman, 1986:1-2).On the other hand, many sociologists have been concerned about theimpact on political sociology of such applications of the rational choice/economic approach to politica l phenomena , and more generally o f sociolog-ically limited frameworks for analyzing thes e phenomena. Moreover, someof them suggest that "we need to examine the degree to which this is afactor in the loss of political sociology [to political scientists and rationalchoice economists] which our discipline created and once dominated"(Light, 1992:909). Hence, the following question arises: Is a rational choice

Games with non-convex strategy sets

The existence of a Nash eq uilibrium point in a $si:n$esi:-person non-c ooperat ive game is proved un der the assumption tha t the strategy sets a re compa ct to pological manifold s cove red by only one cha rt, exce pt for a set of lower topological dim ension The importan ce of thi s result relies on the fact th at in man y situa tio ns of contl rct the stra tegy sets a re not convex. Known methods are of litt le interest because of the int rinsical inability to find examples which satis fies their hyp oth esis Examples are presented, showing there exist various games sa tisfying our hypothesis

On the spontaneous CP violation in the generalized Georgi-Glashow model

Recently L~E has published a paper (1) devoted to the extensive discussion of the spontaneous CP violation in the renormalizable unified models of weak and electromagnetic interactions. One of the main advantages of such approach to the CP violation, as claimed by the author, is the automatic suppression of the CP-odd amplitude which makes unnecessary the introduction of any small parameter into the theory. Such a feature of the theory is highly desirable in view of the rather unfavourable ratio of the number of free parameters in any gauge model to the number of measured quantities characterizing CP violation. The above proper ty of gauge models with spontaneous CP violation is then illustrated in the semi-realistic generalized Georgi-Glashow model with 8 quarks. However, the calculations of CP violating effects were performed under the additional assumption tha t certain couplings in the original Lagrangian consistent with gauge invariance renormalizability and CP invariancc are not important and may be disregarded . The purpose of this note is to prove that the smallness of the CP violation depends crucially on this additional assumption. We shall show that some of the disregarded terms do lead to the effects of the CP violation which arc not suppressed automatical ly and in order to make them small one is forced to introduce some parameters of order 10 -3 into the theory. The couplings which are responsible for the effective CP violation are the Yukawa couplings between triplet of scalar CP-odd fields ez and fermion fields. There are quite a few of them, but for detailed calculations L~E has chosen only the following two terms:

On the stability of a circular motion in the Fokker dynamics

.~.. There is at p resen t a considerable n u m b e r of papers devo ted to the two-body problem in t e rms of the Fokke r type act ion pr inc ip le (~). Such an app roach c~lablcs one to wr i t e down the Lorcn t z cova r i an t equa t ions of mot ion t ak ing into account the finite speed of p ropaga t ion of signals, and is convenicnt when rad ia t ion can bc neglected. However , th is approach invo lves the advanced in te rac t ions and this leads to the ins tabi l i ty of c i rcu la r orbits. I t was shown in (0.-4) t.hat in the cases considered there the f i rs t -approximat ion system (with respect to pe r tu rba t ions of the orbit) admi ts the d ivergen t solutions 9 rod thus the c i rcu la r mot,ion is uns tab le iu t he first approx imat ion . However , we lack corresponding theorems on the o rb i ta l ins tab i l i ty based on the first app rox ima t ion which would al low us to assert t ha t the mot ion is orbi tal ly uns tab le in the case of an exact system. We slal out l ine t he p roof of orb i ta l ins tab i l i ty under the assumption tha t the speeds of par t ic les in c i rcu la r orbi ts are sufficiently small . An analogous theorem wa,~ p roved in (4) for a simplified ease when the dcviat.ions of t he a rgumen t were considered to be constant . Consider the Fokke r type act ion (see (4)) for two par t i c les wi th equal masses (m 1 ~ m 2 ~ m)

Strong gravity and the Yukawa potential

A number of recent papers, seemingly based on very different premises (~-3), have ~uggested tha t the physical d~er ip t ions of ma t t e r on the cosmological level and in the ex t reme microrealm a re s tr ikingly similar. This curious s i tuat ion results from the ut i l izat ion of the formalism of general re la t iv i ty in the analysis of hadronie interactions. Thus the region of space-t ime in the vic ini ty of hadronie ma t t e r is viewed as being ,characterized locally by high curvature, in marked contras t to the t rad i t ional assumption tha t the various part icle interactions occur in the fiat Minkowski background. The coupling of geometry and mat te r effected in Einstein 's equations through the Newtonian gravi ta t ional constant produces, for typical par t ic le mass densities, radi i of curvature (for example) whioh are far too large to be meaningfully in terpre ted in terms of a particle concept. The afore-mentioned works, however, propose the unconventional hypothesis tha t in the region of the hadronie influence the re levant coupling pertains to the strong forces. Wi th this assumption a var ie ty of propert ies of the hadrons can be successfully deduced from the general-relat ivist ic field equations (~-3). One impact of the s t rong-gravi ty model is tha t the strong interact ions should be mediated by massive 2 + mesons (s), quanta of the metr ic tensor field (~) ],~, which satisfies the Einstein equation (~)

Characterization of families of rank 3 permutation groups by the subdegrees I

The conditions on N can be replaced by the assumption tha t N is at least 6 and the intersection number/~ has the value ( q § 1) 2. The cases N----4 and 5 are unsettled even under the assumption tha t /~ has this value. We number the main theorems of this sequences of papers consecutively, Theorems I and I I having appeared in [4]. Theorem I I I can be regarded as a linear analogue of Theorem I I , which in turn corresponds to the case q---1 of Theorem I I I . The subgroups of P F L N (q) transitive on the set of 4-simpliees in PN-1 (q) can be regarded as linear analogues of 4-fold transitive permutat ion groups of degTee N. I t does not appear to be known whether PSLN (q) is always the minimal such group. Since this paper was submitted, D. PE~R~ has proved tha t a subgroup of PTLN (q), q 9 2, which is transitive on the set of k-dimensional linear subvarieties of PN-I(q) for some/c, 2 ~ / c _< [2//2] 1, contains PSLN(q). This implies in particular tha t a subgroup of PI'LN(q), N _~ 6, q :~ 2, which has rank 3 on the set of lines

Multiplicity distribution in pp inelastic collisions

Recently, RIx and the author (7) suggested tha t the dis t r ibut ion over the number of prongs in inelastic hadronie collisions can be explained by assuming I) t ha t the multiplicit ies of pions regardless of thei r charges follow a Poisson dis t r ibut ion and II ) tha t all the possible inelastic final states, which have a given number of part icles and sat isfy the conservation laws of t o t a l isotopic spin, charge and ba ryon number , are equally probable. The predictions of 7:-p inelastic collisions have been given in ref. (1) and agree sat isfactori ly wi th exper iments for P 1 ~ 5 GeV/c. WANG (3), pr ior to our suggestion, proposed a model for mul t ip l ic i ty dis tr ibut ion. He assumed tha t the charged pions in the final states of inelastic hadroulc collisions are produced in pairs in small cells inside the nucleon and tha t the mult ipl ici t ies of these pairs follow a l°oisson distr ibut ion. The neutral pions were also suggested to be produced in the same cellular manner bu t s tat is t ical ly independent of the eharged-pion product ion and these neutrals also follow a Poisson distr ibut ion. The assumption tha t the neutrals and prongs are produced in a s ta t is t ical ly independent manner cannot be exact ly val id because of the isospin constraint . I t is interest ing to invest igate the effect of imposi t ion of isospin constraint on the mult ipl ic i ty distr ibution. Unfor tunate ly , in the case of ~:-p, Wang ' s model cannot predict the dis t r ibut ion for zero prong, and a point to-point comparison of our predict ions wi th his, therefore, is not meaningful. In this connunieation, we will invest igate the mult ipl ic i ty dis tr ibut ion of pp inelastic collisions. Since a zero-prong event is impossible in pp, we ~411 ~chieve a point to-point comparison wi th Wang ' s predictions. Also, the predict ions from Chew and Pignot t i ' s (a) mul t iper iphera l -boots t rap model (hereafter, denoted by CP) will be compared with ours. The calculations will follow closely those in ref. (*). We are going to s t a r t with a Poisson dis tr ibut ion for the number of produced pions m, regardless of the i r charges,

Myth and method in seventeenth-century biological thought

I believe tha t I do not s tand alone in the conviction tha t the greatest m y t h about the seventeenth century, announced with varying degrees of r e fmemen t and historical unders tanding (or misunder s t and ing) , is the belief in a "Scientific Revolution" brought about by the appl icat ion of "the scientific method." Elsewhere and at o ther t imes I have said e n o u g h p e r h a p s too m u c h a b o u t m y general reasons for regarding this half t ruth as an unfor tuna te introduct ion into the terminology of historiography. There are indications that the shibboleth "scientific method" is losing some of its cha rm; but the "Scientific Revolution" we shall a lways have with us, like the "Renaissance"-a fa r worse source of confusion. I have been careful in m y title to employ the adjectival f o rm "biological"; since to talk about seventeenth-century "biology" would not only be a linguistic a n a c h r o n i s m n o very serious ma t t e r pe rhaps -bu t also and m u c h more seriously to force the fluid thought of tha t revolut ionary period into a r igorous f r a m e w o r k and thus pre judge a very impor tan t aspect of the very question I a m to examine . This quest ion involves a correlative prejudice of mine tha t the over-simplification of the historical process implied by the expression "The Scientific Revolution" was the consequence of the very c o m m o n assumpt ion tha t "science" is coterminous with wha t w e t h o u g h not the seventeenth-century p ionee r s ca l l "physics." Of course some of the work of m e n like Niels Stensen and Wil l iam Harvey could be made to look like physics, just as some of the ingenious work of the arch-physicist Mersenne can be made to look like p s y c h i a t r y o r worse. But the ques-

SMALL VASCULAR MALFORMATIONS AS A CAUSE OF PRIMARY INTRACEREBRAL HEMORRHAGE.

O UR experiences with so-called spontaneous intracerebral hemorrhage are repor ted in this paper. We shall not deal with the subject of intracerebral hemorrhage either f rom 1) ber ry aneurysms and angiomatous mal fo rmat ions 12,~7 or f rom ~) hypertensive or atherosclerot ic vascular disease. s,19 The neurosurgeon is familiar with aneurysmal in t racerebral hemorrhage because of the high s tandards of accuracy in clinical diagnosis b y cerebral augiography. The same is t rue for the hyper tensive type of hemorrhage. Cushing, 4 as far back as 1903, had already drawn a t ten t ion to the importance of surgical possibilities for removal of apoplectic hematomas . Extension of the classical type of capsular hemorrhage into the white mat te r , par t icu lar ly into t ha t of the parieto-occipital region, is well known. There is no doubt t h a t the t r e a t m e n t of such cerebral hemorrhages is regarded as highly impor tan t in neurosurgical practice. 5,14,25-27 In addition to these s main groups there is a Srd group wi thou t demonstrable cause of the massive hemorrhage . One popular explanation for this famil iar small group of cases of cerebral h e m a t o m a , frequent in younger persons, is the assumpt ion tha t a small angiomatous mal format ion has been obscured b y the hemorrhage2 9 Although ult imate ana tomica l examinat ion m a y reveal a vascular anomaly , the responsible lesion m a y be difficult to locate because of its situation and its small size. :For these reasons Crawford and RusselP proposed the name "c ryp t i c" for the group of small angiomatous malformations. The incidence of these cryptic h a m a r t o m a s in a necropsy series of 461

Gyrocompass Alignment of an Inertial Platform to Arbitrary Attitudes

The vector control equation is derived which dictates the mechanization for aligning an inertial platform to any arbitrary at t i tude by gyrocompassing and leveling techniques. The derivation is based on the assumption tha t the closed loop for some particular at t i tude is known. To illustrate the vector control equation, a north-zenith-east coordinate system is assumed, and the matrix for forming the proper linear combinations of accelerometer outputs to torque the platform gyros is established. Once the form of the matrix for the north-zenith-east orientation is established, the vector control equation can be used to specify the matrix and the block diagram for any other orientations. Two examples are given: one in which the platform is tilted about the east axis and the other in which the platform is tilted and off north.

Aerodynamic Noise in Supersonic Wind Tunnels

Hot-wire measurements in the free stream of a supersonic wind tunnel were made in the Mach number range of 1.6 to 5.0. I t is shown that the mass-flow fluctuations increase very rapidly with increasing Mach number. If the fluctuation field is assumed to consist of sound waves—an assumption tha t is consistent with the measurements—the sound intensity is approximately proportional to M, within the range of the experiments. Furthermore, the orientation of the field is found to be different from the Mach line direction; it corresponds to a sound-source velocity of approximately one-half the free-stream velocity for the higher Mach numbers. I t is shown that the turbulent boundary layer along the nozzle and the tunnel walls is responsible for this sound field.

Flow Induced by a Cavity in a Supersonic Stream

T ERRATIC BEHAVIOR of a free or partially supported body in the presence of an open bomb bay is probably due to the aerodynamic disturbances generated by the bay. In a practical case, the open bay displays various kinds of stores and equipment so that the shape is very irregular. However, for a first step, it is convenient to idealize the bay as a long, rectangular cutout in an infinite plane (Fig. 1). For the sake of simplicity, the calculations will be carried out on the basis of linearized aerodynamics. ' 2 The underlying assumption tha t the flow deflections created by the body are small cannot be true either at the front or rear of the bay. These are local areas, however, and it is possible that the large features of the flow might be predicted, at least qualitatively, by the linearized theory. The perturbation potential <p(x, y, z) due to a body, symmetrical relative to the plane y = 0,* is

Dynamics of a Gyroscope With Two Degrees of Freedom

Gyroscopes with two degrees of freedom are used to measure the absolute angular velocity of various bodies (aircraft, etc.) (1, 2). The static theory of a two-degree gyroscope starts with the assumption tha t at each instant of t ime the deviation of the gimbal from its reference position in the body is determined by its relative equilibrium under the action of the gyroscopic moment and the moment of the restoring force. This assumption is admissible to a certain extent if the instrument is used only to stabilize the angular position of the object in space or when the disturbing forces on the object are relatively weak. However, when controlling unsteady angular motions of an object or in the case of large disturbances, an estimate of the angular velocity of the object based on static theory may lead to noticeable errors and to the occurrence of false signals. In addition, deviations of the geometric and mass parameters of the instrument from their ideal (rated) values, as occur in actual constructions, impose supplementary errors on the results of the measurement of the angular velocity of the object. I t is therefore advisable to investigate the conditions under which false signals arise in the instrument under arbitrary linear and angular displacements of the object, with allowance for the most substantia] deviations of the actual construction of the instrument from the design data.

The Calculation of Thermoelastic Beam Deflections by the Principle of Virtual Work

which is easily derived from tha t principle. In this formula the beam is assumed to extend from x = 0 to x — L; its cross section has a (principal) moment of inertia I about an axis perpendicular to the direction of v, and its material a Young's modulus E. M(xo) is the bending moment a t any point X — Xo, and MD(XO, x) is the bending moment caused a t X — Xo by a dummy system of loads constructed so tha t it does work if and only if the deflection v occurs a t x; the magnitude of the dummy loads is such tha t this work is numerically equal to v. The principle of virtual work is, of course, of general validity, and holds regardless of whether the beam deflection is due to heating or to actual applied forces. I t is therefore desirable to see whether a simple formula, analogous to Eq. (1), cannot be derived from it for the calculation of thermal deflections of beams, and, further, whether its range of validity is as wide as t h a t of Eq. (1). The purpose of the present paper is the establishment of such a formula. The derivation of an equation of the form of Eq. (1), for the deflection of a beam subjected to an arbitrary temperature distribution, is an easy matter , provided the assumption tha t sections plane before heating reReceived February 24, 1956. f This work was carried out as part of a project sponsored by the U.S. Air Force, and was in part described in the report of reference 1. * Associate Professor of Civil Engineering, Institute of Flight Structures. main plane after heating is accepted and tha t principal axes are employed; i t takes the form

A Study of Surge in Compressors and Jet Engines

C AND J E T engines are occasionally subject to a form of instability called ' 'surging, which usually occurs near the peak of the pressure-flow characteristic and which seems to involve an overall oscillation of flow. Some general surveys and some analyses concerning this phenomenon will be found in references 1 to 6. The present analysis deals with a theoretical model of a je t engine (or compressor, as a special case) consisting of a compressor, a burn ing chamber in which heat bu t not mass is added, and an exit nozzle which is assumed choked so t ha t the turbine has no aerodynamic coupling to the compressor. Shaft coupling between turbine and compressor is assumed to have bu t a secondary effect on the incidence of surge. A number of idealizations (such as the assumption tha t burner temperature varies linearly from inlet to exit) are made in order to render tractable the manipulation of the mass and energy conservation equations as applied to each element of the model. A certain experiment indicates t ha t the character of the airflow in the compressor under transient conditions depends only on the instantaneous flow rate and compressor r .p.m.; this generalization allows a type of entropy conservation theorem to be writ ten for the compressor section. The resulting set of ordinary differential equations must be obeyed by the airflow a t all t imes; it is now necessary to examine these equations to see if solutions exist which oscillate with increasing amplitude. Because of the nonlinearity of the equations, a direct instability analysis is not feasible; therefore it is assumed with reasonable justification t h a t if a solution becomes unstable then so does any perturbation in this solution. The instability of the set of linear equations resulting from perturbation of the original equations is examined, and three analytic criteria obtained.

The Evaluation of Theoretical Critical Compression in Sandwich Plates

Formulas for the critical compression of sandwich plates, which take into account everything that might influence the buckling load, are extremely complex. When simplicity is achieved by concessions in accuracy, the range of validity is not easily distinguished. The evaluations presented here use check points obtained from an exact analysis to test the accuracy of simpler formulas, with the result that one of the latter (proposed in reference 5) is found to be remarkably accurate over a wide range of geometrical and elastic parameters. (1) INTRODUCTION AND SUMMARY OF R E S U L T S THE COMPRESSIVE STRENGTH of thin sheets can be realized only if they are stabilized against buckling. In sandwich construction, two such sheets are bonded to a core slab of different (light) material. The core is sometimes isotropic, sometimes anisotropic. Only the isotropic case is considered here. Panels of this construction give rise to a set of problems of strength, stiffness, and stability analogous to, but by no means identical with, the well-known problems of the ordinary homogeneous and isotropic elastic plate. One of these is cylindrical illustrated in Fig. 1. The panel is so wide tha t lines such as E F can be taken as uncurved. In the ordinary plate, a unit width is treated as a Euler column, but , since anticlastic curvature is prevented, the Young's modulus E is replaced by 12/(1 — v), v being Poisson's ratio.** If it could be assumed t h a t plane sections remained plane, the corresponding sandwich problem would require merely a straightforward modification to take account of the fact t ha t the section is composite ra ther than homogeneous, ff This assumption will be valid when the modulus of the core (Ec) and t h e modulus of the face sheets (Ef) are not too far apart . The sandwich constructions of interest to aeronautical engineers Received February 1, 1951. * The results reported herein were obtained in the course of research studies supported by the Office of Naval Research (Contract N6-ONR-251-TO-12 with Stanford University). f Professor of Engineering Mechanics. X Research Assistant. ** Actually a wide strip must begin to bend with anticlastic curvature, but this curvature does not develop as bending proceeds. There is a transition from E to E/(l — v). The critical load for infinitesimal buckling would appear, therefore, not to require the factor 1/(1 — v), f t See Eq. (11). have light cores with low moduli—not so low tha t they leave the sheets practically free to buckle as independent sheets and not so high tha t plane sections remain plane. The actual buckling is either like column buckling (quasi-Euler buckling) or a short wave wrinkling of the face sheets. In the former, the core m a y exhibit a substantial shearing deformation; in the latter, it acts like an elastic foundation, and the buckling deformation may be confined to the layers adjacent to the face sheets. These s tatements rest on the numerous investigations published during the past 10 years. (A few of these are cited in the list of references.) One group of these deals only with the quasi-Euler buckling, the procedure simplest in principle being the introduction of the correction due to shear in the elementary bending theory. Another group deals with both quasi-Euler buckling and with wrinkling,, treating the core deformation by the methods of the ordinary theory of elasticity. This involves the assumption tha t the (usually small) compressive load borne by the core does not influence its response to lateral forces. A third group goes further by taking this influence into account. The theory used for the core is an extension of the ordinary theory of elasticity developed in the past 20 years which can deal, in general, with elastic deformations in the presence of initial stress severe enough to exert a destabilizing effect; a simple and well-known instance is the lateral loading of an initially compressed bar. The solutions of the sandwich problem so obtained are necessarily complicated. Prior to their appearFIG. 1. Cylindrical buckling of a wide plate in compression.